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From: Peter Zijlstra <peterz@infradead.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: "Barry Song" <21cnbao@gmail.com>,
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Subject: Re: [PATCH 2/2] sched: Centralize SCHED_{SMT, MC, CLUSTER} definitions
Date: Fri, 15 Oct 2021 15:04:50 +0200	[thread overview]
Message-ID: <YWl8cogsS2Lah1mk@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <87bl3zlex8.mognet@arm.com>

On Fri, Oct 08, 2021 at 04:22:27PM +0100, Valentin Schneider wrote:

> So x86 has it default yes, and a lot of others (e.g. arm64) have it default
> no.
> 
> IMO you don't gain much by disabling them. SCHED_MC and SCHED_CLUSTER only
> control the presence of a sched_domain_topology_level - if it's useless it
> gets degenerated at domain build time. Some valid reasons for not using
> them is if the architecture defines its own topology table (e.g. powerpc
> has CACHE and MC levels which are not gated behind any CONFIG).
> 
> SCHED_SMT has an impact on code generated in sched/core.c, but that is also
> gated by a static key.
> 
> So I'd say having them default yes is sensible. I'd even say we should
> change the "If unsure say N here." to "Y".

Right, so I tend to agree (and also that we should fix that Kconfig help
text). But it would be very nice to have feedback from the affected arch
maintainers.


      reply	other threads:[~2021-10-15 13:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-08 11:53 [PATCH 0/2] sched: cleanup CONFIG_SCHED_MC & friends Valentin Schneider
2021-10-08 11:53 ` [PATCH 1/2] sched: Move Kconfig.preempt to sched/Kconfig Valentin Schneider
2021-10-08 11:53 ` [PATCH 2/2] sched: Centralize SCHED_{SMT, MC, CLUSTER} definitions Valentin Schneider
2021-10-08 12:37   ` Barry Song
2021-10-08 15:22     ` Valentin Schneider
2021-10-15 13:04       ` Peter Zijlstra [this message]

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